Enviro Perspectives on Camouflage with Dave Rushworth
Moths - Questionable Camouflage
Our excellent array of field guides and other reference books record what is known about most aspects of natural history. There is still a huge field of knowledge to be discovered and no interested person should stop searching beyond present boundaries. Of a presumed six million insects only around one million have been described.
Moths are no exception and of the hundreds of thousands know to exist, most have not been named or described. The larger, most colourful or economically important ones are quite well recorded but small, cryptic ones remain largely undiscovered.
Camouflage And Predation
The presumption is that moths (and other animals) are camouflaged to avoid detection and predation.
Many species have gaudy patterns and colours which we presume serve as warning against unpalatability or function for inter-specific contact. Many cases of this presumption have been acceptably demonstrated but there are still many ponderables.
Camouflaged species often have brighter colours or patterns on the lower wings. These features, which are normally hidden, become obvious in flight or with wings open and may be effective in aerial predation or static displays.
For most evenings over a couple of years I have been observing and photographing certain grey tree frogs and their interaction with moths and other insects attracted to lights.
The frogs are generally regular and consistent in their position and behaviour. The insects appear in species and numbers dependent on weather conditions. Observations indicate that frogs will not take static (non-moving) prey species.
The prey has to be moving, although moths emitting pheromones and flapping at a particular fast frequency are generally ignored. Although frogs are presumed to see colour, the patterns and colour of the prey has no effect on predation, despite 'warning colours' and presumed toxins.
Size of prey is only limited by the size of the frog. Uncomfortably hard and spiky prey (such as certain beetles) taken by mistake, are immediately spat out.
Birds and reptiles are mostly attracted to moving prey but few appear to be discouraged by (what we presume to be) warning colours and patterns. Are all our learned and persistent presumptions correct?
- If camouflage is so effective - why the need for 'warning' colours? During movement only? Apart from very cryptic activity - movement overrides camouflage. If colours don't work on observed frogs - when are they effective? Warning patterns that are obvious when static would appear superfluous - or do they break up familiar outlines, as presumed in the case of stripes on zebra ? Do all 'buzzing' tones have significance - as in the case of the spider wasps ?
Is flapping frequency significant protection during 'pheromone emission' ? It would appear that certain, presumed toxins are prey specific - effective only against certain species. Is this correct?
If insects and rodents are killed by pesticides, are their still, dead bodies really eaten by predators - or is it the 'wobbly' ones that are taken before they die?
There is so much we don't know and so many false presumptions that we perpetuate without question. Conduct your own observations and research in the interests of further information and I hope this will stimulate some response.